1. Field of the Invention
The present invention relates to an adjusting method and an adjusting system for a sensor, which is used for detecting a position of an actuator-driven mechanical load arranged in a variable valve mechanism for variably changing open characteristics of an engine valve, in accordance with the position of the mechanical load.
2. Description of the Related Art
Japanese Laid-pen (Kokai) Patent Application Publication No. 2005-299578 discloses a variable valve mechanism in which lift amount of an intake valve of an internal combustion engine is continuously changed in accordance with the rotation position of a control shaft of the variable valve mechanism, which shaft behaves as a mechanical load.
Further, the above-mentioned publication discloses the technique that an output characteristic of a sensor for detecting a rotation position of the control shaft is learned based on an output of the sensor in a state where the control shaft is actuated to rotate so as to minimize the lift amount of the engine valve.
In the case where a mounting position of the sensor is in misalignment with a regular position at the time of replacement of the sensor, the output of the sensor is liable to exceed a tolerable input range of a processing circuit.
Once the sensor output exceeds the tolerable input range of the processing circuit, the rotation position of the control shaft cannot be correctly detected from the sensor output even in the case where the sensor output is learned at the time of the minimum lift amount of the engine valve as described above.
As long as the sensor output is higher than the tolerable input range of the processing circuit, therefore, it is unavoidably necessary to make adjustment of the mounting position of the sensor.
Nevertheless, the variable valve mechanism disclosed in the aforementioned publication is not equipped with any means such as a return spring or the like for achieving automatic restoration of the control shaft to a specified position, and therefore, the rotational position of the control shaft may become uncertain when the engine is stopped and the actuator is stopped to drive the control shaft.
The variable valve mechanism described above, therefore, must pose such a problem that it is difficult to accurately adjust the mounting position of the sensor for detecting the rotation position of the control shaft.